1. Field of the Invention
The present invention relates in general to a telephone set (a combination of a telephone transmitter and a telephone receiver) which has an automatic selective facsimile/telephone reception mode (hereinafter referred to as "F/T reception mode") and is capable of generating a ringing sound after the telephone set of a called party is connected to a remote telephone set of a calling party. More particularly, the present invention is concerned with a telephone set of distinctive ringing type which uses two or more telephone numbers and which is adapted to receive call signals having different patterns which call the respective telephone numbers and generate ringing sounds of different patterns depending upon the patterns of the received call signals even after the telephone set is connected through a telephone line to the remote calling party.
2. Discussion of the Related Art
There is known a telephone set adapted to utilize a so-called "distinctive ringing service (D/R service)" available from a telephone exchange company. This telephone set of distinctive ringing type uses two or more telephone numbers on one telephone line. The distinctive ringing service provides the telephone set with telephone call signals which have different patterns as illustrated at (a) through (d) in FIG. 20, when the respective telephone numbers are called by a remote telephone transmitter of the calling party, so that the ringing device of the facsimile system of the receiving or called party generates different types of ringing sound depending upon the telephone numbers being called.
Where such a telephone set of distinctive ringing type is incorporated in a facsimile system as a telephone portion thereof, one of the telephone numbers is used exclusively for facsimile communication with a facsimile portion of a remote facsimile system, while the other telephone number or numbers is/are exclusively used for telephone communication with a telephone portion of the remote facsimile system. The telephone number called by the remote facsimile system of the calling party can be recognized by the specific type of the ringing sound generated according to the specific pattern of the appropriate call signal received at the called party. In this case, the pattern of the facsimile reception call signal assigned to call the telephone number exclusively used for the facsimile communication is registered in memory means at the called party. When the telephone set at the called party receives a call signal from a telephone exchange company, the pattern of the received call signal is compared with the registered pattern of the facsimile reception call signal, and a facsimile signal received with the call signal is automatically processed for recording of an image represented by the facsimile signal, if the pattern of the received call signal is the same as the registered facsimile reception call signal pattern. An example of such facsimile system of distinctive ringing type is disclosed in JP-A-4-48855.
The distinctive ringing service is also useful and convenient where two or more users use one or more telephone sets connected to one telephone line. In the case where a facsimile system incorporating one telephone set using three telephone numbers is used by Messrs. A and B, for example, the telephone number [1111] is used as the facsimile reception telephone number, and the telephone numbers [2222] and [3333] are used for telephone communication by Mr. A and Mr. B, respectively. Mr. A informs the potential calling parties that Mr. A uses the telephone number [1111] exclusively for facsimile reception and the telephone number [2222] exclusively for telephone communication, while Mr. B informs the potential calling parties that Mr. B uses the telephone number [1111] exclusively for facsimile reception and the telephone number [3333] exclusively for telephone communication. A facsimile signal addressed to Mr. A or Mr. B by the corresponding call signal is automatically received (converted into the corresponding image). When a call signal calling the telephone numbers [2222] or [3333] is received, the user can find out whether the telephone call is addressed to Mr. A or Mr. B, by listening to the ringing sound generated according to the specific pattern of the call signal. That is, the different patterns of the ringing sounds enable the users to determine the telephone number being called.
Some telephone sets of distinctive ringing type are adapted to generate ringing sounds after the telephone sets are connected through the telephone lines to the remote telephone sets upon reception of respective call signals. In a facsimile system incorporating such a telephone set and having a F/T reception mode, a ringing sound is first generated according to a received call signal after the facsimile system of the called party is connected to the remote facsimile system of the calling party. If a facsimile signal transmission signal CNG (calling tone signal) is received following the call signal, a ringing device generating the calling sound is turned off, and a facsimile signal if received following the signal CNG is automatically processed for image recording. The signal CNG indicates that the facsimile signal will be transmitted from the remote facsimile transmitter. Even if the signal CNG is not received, the ringing device is turned off and the facsimile signal if received is automatically processed if the telephone hand set at the called party is not picked up for more than a predetermined time after the call signal is received from the remote calling party. If the telephone hand set is picked up within the predetermined time, telephone communication with the remote telephone set is made possible.
However, the call signal from the telephone exchange company is no longer received after the facsimile system of the called party is connected through the telephone line to the remote facsimile system of the calling party. Hence, the generation of the ringing sound after the call signal from the telephone exchange company is cut off should be effected according to a given ON-OFF pattern preset in the telephone set at the called party. This means that the telephone set cannot utilize the distinctive ringing service (D/R service) that permits the generation of ringing sounds of different patterns depending upon the telephone numbers being called by respective call signals of different patterns.